The present invention relates generally to surgical instruments and more particularly to surgical instruments that engage body tissue by means of applied vacuum, such as suction stabilizers and suction retractors employed in coronary artery bypass surgery.
In order to avoid the risks and difficulties associated with cardiopulmonary bypass, various procedures for performing coronary artery bypass on the beating heart have been developed. Several of these procedures employ devices which stabilize a desired anastomosis site by means of suction pods placed on either side of the anastomosis site and devices which hold the heart in a desired position by means of a larger suction pod, typically placed on or near the apex of the heart. Devices of the first type are referred to herein as xe2x80x9csuction stabilizersxe2x80x9d. Devices of the second type are referred to herein as xe2x80x9csuction retractorsxe2x80x9d. It is common for procedures to be performed using one of each type of device.
In procedures where both a suction stabilizer and a suction retractor are employed, it is conventional to attach each of the devices to a vacuum source through a separate vacuum regulator and associated canister. While both the stabilizer and the retractor could be coupled to a single vacuum regulator, this is not typically done because a loss of vacuum attachment by one device could readily trigger a loss of vacuum attachment by the other device. The consequences of this loss of attachment would be particularly severe in the context of the suction retractor. However, as sudden detachment of either type of device is undesirable, physicians have typically employed separate vacuum regulators, canisters and vacuum lines for each suction device, in spite of the fact that this results in significant additional equipment being present in the operating room and additional complexity in equipment set-up, as compared to the use of a single vacuum regulator.
The present invention allows the use of a single vacuum regulator and associated canister to provide vacuum to two suction devices, and in particular to provide vacuum to a suction stabilizer and a suction retractor concurrently. The invention accomplishes this result by means a vacuum controller or controllers associated with the suction devices, located in the vacuum line between the vacuum regulator and the suction device. In operation vacuum controllers may be placed in the vacuum lines provided to each of two or more suction devices, or may be placed only in the vacuum line of the suction device believed most likely to detach during the procedure.
Each vacuum controller is provided with a primary vacuum line, coupling its associated suction device to the output of the vacuum regulator and a pilot passage for coupling the suction device to the vacuum regulator. The controller closes a valve in the main vacuum line in response to loss of vacuum attachment, which valve remains closed until attachment is reestablished. Closure of the valve results in substantial or complete blockage of the main vacuum line, depending on the particular form of the invention. The portion of the main vacuum line between the valve and the suction device is referred to herein as the xe2x80x9cdownstreamxe2x80x9d portion of the line, while the portion of the main vacuum line between the valve and the vacuum regulator is referred to herein as the xe2x80x9cupstreamxe2x80x9d portion of the line. The pilot passage serves to allow reestablishment of vacuum attachment while the main vacuum line is closed. The pilot passage is configured so that airflow through the pilot passage is low enough that the other suction device or devices coupled to the vacuum regulator can still maintain vacuum attachment.
In a first embodiment of the invention, the controller is provided with a solenoid valve in the main vacuum line, coupled to a vacuum switch that monitors vacuum in the downstream portion of the main vacuum line. The vacuum controller also includes a battery for powering the solenoid valve and may optionally include a voltage indicator, to indicate the condition of the battery. In the event that vacuum attachment of a the device coupled to the controller is lost, the vacuum in the main vacuum line will rapidly drop and the switch will shut the solenoid valve in the main vacuum line, leaving the pilot line open. When the detached suction device is reapplied to the heart""s surface, vacuum applied through the pilot passage serves to reestablish vacuum attachment and to reestablish vacuum in the downstream portion of the main suction line. Restoration of vacuum in the main vacuum line in turn triggers the vacuum switch to open the solenoid valve on the main suction line, restoring full vacuum to the reattached device.
A second embodiment of the invention employs a vacuum operated valve in the main vacuum line. The valve is maintained in an open position by the vacuum in the downstream portion of the main vacuum line. When vacuum attachment of the associated suction device is lost, the vacuum operated valve closes the main line. When vacuum is restored in the downstream portion of the main vacuum line due to reattachment of the device, the valve opens the main vacuum line and provides full vacuum to the suction device in a manner analogous to that described above.
In either the first or second embodiment of the invention, the pilot passage may take various forms. In one form, the pilot passage is a separate line, parallel to the main vacuum line, but bypassing the valve in the main vacuum line. In such cases, flow through the pilot line will be limited either by the size of the line itself or by a flow limiter such as a needle valve or other restrictive orifice. In an alternative form, the pilot passage may be associated with the valve. In some cases, the pilot passage may be defined by the valve itself, and may provide for limited flow through the valve while the valve is closed. This desired result can be accomplished, for example, by a separate limited flow passageway moved into position between the upstream and downstream portions of the main vacuum line during valve closure. Alternatively, the valve may simply be configured to allow a defined level of leakage in the closed position. In other cases, the valve may instead switch the connection of the upstream portion of the main vacuum line to a pilot line, in turn coupled to the downstream portion of the vacuum line and to the suction device.
The vacuum controllers may be compact, relatively simple and inexpensive devices that may either be disposable or reusable. The controllers may be located at any convenient location within the operating room along the length of the vacuum lines to the suction devices.